Process for conditioning metal ingot molds



R. K. HoPKNs 'mocmss FOR coumnoume METAL' Iueo'r MOLDS iled April 7, 1944 May '1, 1945.

Patented May 1, '1945 PROCESS FOR OONDITIONING METAL NGo'rMoLns Robert K. Hopkins, New York, N. Y., assignor to The M. W. Kellogg Company.- New York, N. Y.. a corporation of Delaware Application April "I, 1944, Serial No. 530377 2 Claims.

Thepresent invention relates to a process for conditioning metal ingot molds.

The repeated casting of ingots in metal molds tends to cause the mold wall to warp severely if they are comparatively thin, and to check and warp if they are comparatively thick. This is due to the intense heating of the inner peripheral mold wall section while the remainder of the mold wall lags far behind in temperature. Under these conditions, the inner periphera section of the mold wall tends to increase in length but is restrained by the rest of the mold wall. ,The mold wall, therefore, upsets itself each time an ingot is cast. Prolonged repetition of this thermal strain i 'will so deform the mold, and will so reduce its diameter as to materially impair its usefulness.

I have found if the mold'is sized to its original internal dimensions periodically and before the deformation has become excessive its usefulness may be prolonged indefinitely.

One object of the present invention is to provide a new and improved process for sizing a mold to proper internal dimensions.

Another object is to provide a new and improved process by which a mold is periodically sized and treated to prevent excessive accumulated deformations or upsets, and to render it continuously in proper condition for prolonged 'usej A further object is to provide a new and immade of suitable metal such as cast steel or copper, and open at both ends. such a mold o is adapted to be supported in an upright casting position on a stool forming a closure for the bottom of the mold. After the mold o ha repeatedly been used for casting', it may ,become warped and deformed, and may also become upset in its inner peripheral section to an extent sufiicient to materially reduce its internal diameter, as already described.

In accordance with the process of the present V original internal dimensions before the deformation becomes too pronounced and before-cracks and checks develop on its internal surface. For, if cracks and checks are allowed to develop these will not be removed by the sizing operation.

One suitable working method which may be employ'ed in accordance with the present invention involves the use of an expanding or sizing tool ii to mechanically work the interior of the mold lo. This sizing tool Il may be of any suitable conventional type, and is shown for the purpose 'of illustration comprising a head z mounted on a proved process for reconditioning metal ingot main shaft !3, and carrying a plurality of cirmolds after their usefulness has been impaired by repeated use.

Another object is to provide a process for easily, efiectively and expeditiously reconditioning metal ingot molds deformed and upset by the irregular thermal strains resulting from casting operations. various other objects of the invention will be apparent from the following particular description, and from an inspection of the accompanying drawing. in which: V

Fig. 1 is a partial vertical longitudinal section showing a unitary metal mold being conditioned in accordance with a process constituting one embodiment of the present invention;

Fig. 2 is a transverse section taken on line of Fig. 1;

Fig. 3 isa transverse section of a split metal mold which may be conditioned in accordance I with the process of the present invention: and

Fig. 4 is a transverse section showing one of the split sections of the mold of Fig. 3 being conditioned in accordance with a process constitutin another embodiment of the present invention.

Referring to Figs. 1 and 2 of th drawing. there is shown a one-piece cylindrical ingot mold lll action a described, the mold cumferentially spaced pressure rollers ld. These pressure rollers Il are journalled at their ends in 'two rings !5 keyed to a stub head shaft iS, and

separated by a spacer IT also keyed to said head. shaft. A nut IS threaded on the head shaft i& and bearing indirectly against a clamping plate !9 serves' to hold rigidly the roller retaining ring unit IE on said head shaft and against a flange 20 on said head shaft. Studs 2I detachably fasten the sizing head z to the main shaft !3, so that a sizing head of any desired rolling diameter may be removably attached to said main shaft.

To roll and thereby condition the mold lil. the sizing head I2 is for-med into the mold with its rollers I& in pressure rolling contact with the inner periphery of said mold. The outer circumferential circle of these rollers It is fixed to correspond to the desired internal diameter of the reconditioned mold ID.

The sizing head !2 is forced axially and rotatively ini the'interior of the mold o to assure mechanical working of the entire inner peripheral section of said mold. If desired, instead of moving the sizing head !2 for mechanical workin lil may be worked by rotating said mold and simultaneously advancing it axially over the sizing head while said head is held in fixed position. p

Instead of employing a sizing tool having a fixed rolling diameter, a sizing tool may be employed of the conventional type in which the rollers canbe adjusted radiaiiy outwardly to vary the rolling diameter of the tool. such an adjustable sizing tool may, for example, be used to condition a mold of the big end or tapering type. When used for that purpose, the sizing tool may be adjusted while it is being advanced along the interier of the taper ing mold, so that itsoperating rolling dimension may be varied to conform with the varying diameter of the mold interior.

The mold o may be subjected to a number of rotary and axial rolling passes as described, according to the extent of mold impairment. The internal mechanical working operation described straightens, ii'ons out and trues the warped mold n, forces its particles into more intimate contact, and refines its crystalline structure, so that the mold will be. restored into sound condition for continued prolonged use. At the same time, any upset in the inner peripheral section of the mold o, resulting in a reduction in its internal diameter, is corrected by restoration of said mold to its original internal diameter.

The mold n may be subjected to the' reconditioning operation described periodically whenever it is necessary. It is desirabie to recondition the mold o before it becomes excessively deformed, warped or upset. Under certain conditions, for example, it may be desirabie to roll the mold at the end of each casting operation. In this manner, the mold o can be' maintained in proper condition for indefinite use with a minimum of eifort.

Fig. 3 shows a diametrically split form of cylindrical mold provided with comparatively thin walls and .consisting ot two similar semicircular sections 26 made of copper or other suitable metal having high heat conductivity. These mold sections 26 have radially outwardly extending flanges 21, and are Secured together by a series of bolts 23 passing through these flanges.

In sizing molds of the sectionai thin-walled type shown in Fig. 3,-diflicu1ty may be encountered in the use of a sizing tool, since this tool during rolling Operations tends to float over the internal mold deformations. To assure a proper sizing and conditioning ot a sectionai mold oi' the type shown in Fig. 3, a telling process may be em loyed, such as that shown in Flg. 4. For that purpose, a block 30 is employed having a finished semi-.- cylindricai gauge channel si oi a diameter corresponding exactly to the original internal diameter of the sectiona mold 25.

In condition'ing the mold 25, its two sections 26 are separated, and one of the sections is rigidly mounted on the sizing block 30 by suitable festening means, such as studs 32, so that the semicylindrical hollow of said latter section forms with the block channel 3! an approximately round cavity. The sizing head I2 is rotatively and axially forced through this cavity to mechanically work the spiit mold section 26, so that it is conditioned for further use. During this working operation. the block 30 serves as a rigid support for the sizing head [2, thereby permitting proper expansion of the mold section 26 to its proper size and condition. When the conditioning process on this mold section 26 has been completed, the other mold section 26 is then subjected to the same working process:

As many changes can be made in the above process, and many apparentiy widely difl'erent embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. The process of conditioning a diametricaily split cylindrical mold, which eomprises mounting one of the semi-cy1indrica1 sections of the mold on. a sizing block having a semi-cylindrica channel, so that said channel and the hollow of said mold section form a common cavity, said block channel having a diameter corresponding'to that to which it is desired to expand said mold section, passing a sizing rolling tool through said cavity to expansively work the inner periphery oi' said mold section to the correct and subjecting the other mold section to a similar working treatment.

2. The process of reconditioning a longitudinal split cylindrical metal mold worn by unequal ther-mal strains set up during casting Operations, which comprises mountng one of the sections of the mold on a sizing block having a channel of circuar cross-section conforming in diameter to the original internal diameter of the mold, said mold section being mounted in said block so that its holiow forms with said channel a common substantially round cavity, passing a sizing rolling tool axially and rotatively through said cavitv to expansively work the inner periphery of said mold section to the correct size and iron out any internal deformities in its inner periphery, and repeating said working process with the qther mold section, whereby said mold sections are restored to sound condition for continued use.

ROBERT K. HOPKINS. 

